How Does Nitrous Oxide Work?

This
Question of the Day talks about how sodium chlorate acts as a way to
store oxygen. You release the oxygen in sodium chlorate by heating it.
It turns out that nitrous oxide (N20) works exactly the same way. When
you heat nitrous oxide to about 570 degrees F (~300 C), it splits into
oxygen and nitrogen. So the injection of nitrous oxide into an engine
means that more oxygen is available during combustion. Because you have
more oxygen, you can also inject more fuel, allowing the same engine to
produce more power. Nitrous oxide is one of the simplest ways to
provide a significant horsepower boost to any gasoline engine.

Nitrous
oxide has another effect that improves performance even more. When it
vaporizes, nitrous oxide provides a significant cooling effect on the
intake air. When you reduce the intake air temperature, you increase
the air's density, and this provides even more oxygen inside the
cylinder.

The only problem with nitrous oxide is that it is
fairly bulky, and the engine needs a lot of it. Like any gas, it takes
up a fair amount of space even when compressed into a liquid. A 5-liter
engine running at 4,000 rotations per minute (rpm) consumes about
10,000 liters of air every minute (compared to about 0.2 liters of
gasoline), so it would take a tremendous amount of nitrous oxide to run
a car continuously. Therefore, a car normally carries only a few
minutes of nitrous oxide, and the driver uses it very selectively by
pushing a button.